Simultaneous multicolor printing



Oct. 26, 1965 c. s. MILLER SIMULTANEOUS MULTICOLOR PRINTING 2Sheets-Sheet 1 Filed Jan. 26, 1956 Oct. 26, 1965 c; s. MILLER 3,213,787

S IMULTANEOUS MULTICOLOR PRINTING Filed Jan. 26, 1956 2 Sheets-Sheet 2United States Patent 3,213,787 SIMUILTANEOUS MULTICULOR PRINTING Carl S.Miller, St. Paul, Minn., assignor to Minnesota Mining & ManufacturingCompany, St. Paul, Minn., a corporation of Delaware Filed .Iau. 26,1956, Ser. No. 561,426 12 Claims. (Cl. 1012l1) This invention relates tomulticolor printing, particularly as applied to intaglio or photogravureprocesses. The invention relates to the novel method, and to novelcomponents employed therein.

In a typical prior art continuous process for gravure printing, acylindrical surface is provided with an engraved recessed design, whichwhen filled with a suitable colored ink and pressed against a papersurface then produces a printed reproduction of the design. Formulticolor prints, the several colors are applied from successivegravure cylinders, the paper being passed in registry and in successionover the several cylinders required. The process thus requires thepreparation of a number of separate printing cylinders by processesinvolving color separation of the colored original, and the exactregistry of the several cylinders in their contact with the paper orother surface on which the final multicolor reproduction is to beimpressed.

The present invention permits the printing of multiple color impressionsby a single contact with a single printing cylinder which is fed from asingle source of printing ink. The problem of exact registry iseliminated. Shrinkage or expansion of the paper, or weaving of the paperweb through the printing apparatus, may be tolerated. The printingapparatus is greatly simplified, and need not be subject to precisioncontrol. The time required for setting up the press and for cleaning upafter the completion of the run is drastically reduced. Clear andsharply outlined copy, having accurate color rendition, is obtained.

These and other advantages are secured, in accordance with theprinciples of the present invention, by providing on the gravurecylinder a plurality of types of image printing cavities, each typebeing selective of a particularly colored printing composition, theseveral types of image printing cavities being located on the surface inaccordance with the arrangement of color (hue) in the graphic subjectmatter or other colored original of which a duplicate is desired. Thethus treated cylinder is simultaneously fed with a plurality of mutuallyincompatible inks of suitable color, either at separate inking stationsor as a mixture of the differently colored inks applied at a singlestation. Each ink composition is capable of selectively wetting andadhering to one of the specific types of image printing cavities.Surplus ink is removed from the surface of the cylinder by conventionalmeans, the paper is pressed against the surface, and the separate andindependent quantities of the several colored inks initially retained inthe different types of image printing cavities are thus transferred tothe paper to provide, in a single step, a multicolor print.

The operation as thus briefly described has been successfully applied totwo-color and to three-color printing, by means of techinques andmaterials which will now be described in detail in connection withspecific but non-limitative examples, and by reference to the at tacheddrawing, in which:

FIGURE 1 is a cross-sectional representation showing in simplfiedschematic form the apparatus and procedure employed in the process ofthis invention;

FIGURE 2 represents a cross-section of a portion of a recessed andtreated surface of the printing cylinder;

FIGURE 3 represents a plan view of a portion of the surface of thetreated cylinder of FIGURE I2;

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FIGURE 4 represents a plan view of a portion of a base sheet used inpreparing screen elements employed in the practice of this invention;and

FIGURE 5 is a cross-sectional representation illustrating one processfor the selective activation of cavities.

Example 1 A copper printing cylinder is first provided with a recesseddesign, by methods which will be more fully described hereinafter, toproduce a recessed surface somewhat as illustrated in FIGURES 2 and 3 inwhich alternate pockets represent different colors in the originalarticle, print, picture or other subject of which a reproduction isdesired. The depth of each cavity is deter mined by the intensity(value) required for that particular color at the particular point. Theindividual cavities, which may be of any desired uniform configurationbut for convenience are shown in FIGURE 3 as square-shaped, areseparated by ridges, the tops of which are all in the plane of theoriginal surface of the printing cylinder. In FIGURE 2, cavities 1 and 4represent different values of a first color, cavities 2 and 5 repre sentdifferent values of a second color, and cavity 3 represents still athird color and value. The ridges 6, lying in the plane of the originalsurface of the roll 7 of FIGURE 1 (of which a portion only isillustrated in FIGURE 2) separate the several cavities from each other.

The copper surfaces of the cavities 1 and 4 are treated with a 2 /2percent aqueous solution of ammonium sulfide, providing a hydrophilicsurface presumably comprising copper sulfide.

The surfaces of cavities 2 and 5 are treated with a dilute solution in avolatile solvent of an organic silicone, such as Dow Corning siliconevarnish No. 996 or No. 997, and which is believed to be largelypolymethyl silicone in an organic solvent, to provide an organophilicsurface.

Cavity 3 is treated with a three percent solution in xylene hexafluorideof polymerized dehydroperfluorooctylmethacrylate, to provide a surfacewhich is receptive to fluorochemicals and may therefore be designated alimophilic surface.

Treatment of the cavity surfaces with the different solutions suggestedmay be accomplished, Where the cavities are not too small, by carefulhand application of the solution with a pointed brush or hypodermicneedle, care being taken to avoid spreading of the solution across thesurrounding ridges into adjacent cavities. After drying, the thustreated cylinder is thoroughly washed, for example in alternate baths ofwarm water and solvent naphtha, to remove all soluble salts withoutdisturbing the treated surfaces. The cylinder 7 is then ready for theprinting operation and is placed in the press, as indicatedschematically in FIGURE 1.

Three different and mutually incompatible ink formulations are nextprovided, in the conventional three subtractive colors.

The magenta ink is compound with a water base and contains the followingcomponents in the weights indicated:

Calcium lithol toner (Calco 20-4620) 15 Methyl cellulose (Methoce1X2602), 10% solution in water 50 Glycerol 5 Polyethylene glycol(Polyglycol P-3000) 1 Water 129 The pigment is ground into the solutionof binder and plasticizer, forming a smooth homogeneous liquid producthaving a viscosity of approximately 1.25 poise, as determined on theGardner bubble viscosimeter.

3 The yellow ink is compounded with an oil base. The formula is:

Yellow oil-soluble dye (FDC Yellow No. 4) 1 Xylol l4 VM & P naphtha 85The dye is dissolved in the mixed solvents. The viscosity of thesolution is about 0.45 poise.

The cyan ink is compounded of a fiuorochemical color body and afluorochemical vehicle, as follows:

'Perfiuoroheptylated copper phthalocyanine 4 Perfiuoroethylcyclohexane96 The two components are vigorously shaken together,

forming a stable liquid mixture having a viscosity of about 0.35 poise.

The fluorochemical color body is appropriately produced by heatingtogether 1.4 grams of copper phthalocyanine (MonastraP blue, acommercial pigment) and 10.0 grams of perfluoro-n-heptyl iodide, n-C FI, in a 30ml. glass ampoule at 330 C. for 14 hours. The reaction productis extracted with c-C F O, and the intensely blue solutionis evaporatedto dryness, leaving 2.7 grams of dark blue-black powder. Furtherextraction of the filtration residue with benzotrifiuoride (CF C Hprovides an additional yield of 1.7 grams of the color body. Both of theproduct materials are found on analysis to consist mainly oftetraperfluoroheptyl copper phthalocyanine, having the empirical formulaC F H N Cu.

Each of these ink compositions is a low-viscosity liquid,

whereas prior art lithographic inks are conventionally vis cous orpaste-like materials. For example, a typical lithographic ink suchasused on a Multilith office printing machine has a soft butteryconsistency and cannot be tested on a bubble viscosimeter. These variousviscosity or consistency values are each given at room temperature.

Appropriate quantities of each of the three inks abovedescribed areadded to the inking fountain 8 of the apparatus of FIGURE 1. The threeliquids arrange themselves in separate layers, the cyan ink being at thebottom, the yellow at the top, and the magenta between. The cylinder 7contacts each of the liquid layers, and rotation of the cylinder bringseach liquid into positive contact with each part of the cylindersurface. The several liquids adhere strongly to appropriately treatedareas of the surface and are displaced from temporarily contacted areasof different surface characteristics. Thus, the aqueous liquid remainsexclusively on the sulfide-treated surfaces, the hydrocarbon liquidremains only on the silicone-treated surfaces, and the fiuorochemicalliquid is retained only on the fluorochemical-treated surfaces.

Excess ink is removed from the surface of the cylinder 7 by thedoctor-blade 9 and returned to the fountain 8. The blade rides on theridges 6 of the'recessed surface of the cylinder, providing accuratecontrol of the amount of ink retained in each cavity. Although theliquid is low in viscosity, the small size of the cavities and thenature of the treated surfaces is found to cause the liquid to beretained in the cavities while the cylinder is rotated past thedoctor-blade and to the printing position.

The ink-treated surface is next contacted with a sheet or strip of paper10, here shown as supplied from stock roll 11. The paper is pressedfirmly against the cylinder by means of an impression cylinder 12, andthe ink is transferred to the ink-receptive surface. The printed sheetthen desirably passes over a heat source 13 for removal of volatiles,and is wound up into stock roll 14 or stacked up in sheet form.

The inks are transferred from the treated surfaces of the cylinder tothe surface of the paper in a pattern established by the arrangement ofthe treated cavities in the cylinder surface. The three colors aresimultaneously applied. The resulting print is in full color, and thecolors are in perfect registry regardless of changes in humidity orother causes of dimensional instability in the paper.

Printing with three basic colors, viz., yellow, magenta and cyan,provides full-color reproductions and is required for most effectiveresults. The process hereinabove described, using the combination ofcomponents indicated, now for the first time makes possible full-colorprinting in a single operation, with the simultaneous application ofinks of all three required subtractive colors; and such processes aretherefore greatly preferred. It will be apparent that the sameprinciples may be applied also to two-color printing, employing anydesired pair of mutually incompatible inks and appropriate treatments ofthe printing cylinder, and may also be expanded to include printing infour or more colors where suitable inks and suitable surface treatmentsare provided.

In conformance with recognized authority, color or hue here refers tothe particular shade, either additive or subtractive, such as red,magenta, blue, green, cyan, yellow or the like; and value refers to theintensity of the color, thus covering such gradations as pink, lightred, bright red, etc. It has been found that prints having a wide rangeof hue and value may be produced from three subtractive colors by theprocedures and with the type of ink compositions hereinbefore described.While it is not desired to be limited to any particular theory ofoperation, it is believed that the lateral flow of ink along individualfibers or betweenadjacent fibers of the paper effectively providesoverlapping colored areas and makes possible the subtractivetransmission of light, thus providing the unique and highly desirableresults attained. Effective lateral flow of color components may also beobtained with surface coatings of mixtures of suitable treated clay orother particulate materials, or in other ways.

Printing may also be accomplished on surfaces which prevent the lateralflow of ink. For example, various films and foils may be printed inmulticolor in a single operation. In such cases the separate small areasof ink may remain as separate dots of color, to give an impression ofuniform coloring when seen from a sufficient distance; and additiverather than subtractive colors will normally be used. It will also beapparent that colorless compositions of various kinds, such as liquidscapable of selectively swelling or dissolving, or chemically reactingwith, a surface to which they are to be applied, may equally well beprinted in multiple and on selected areas in a single operation bymethods employing the principles of this invention.

A number of other surface treatments are available which may besubstituted for the specific surface-activating treatments and formulas,as applied to the cavities of the copper cylinder in the above specificexample. A hydrophilic surface, suitable for retaining aqueous inks, maybe obtained by treating the prepared copper cylinder with dilutesolutions of sodium thiosulfate, or sodium sulfide, or mixtures ofsodium sulfide and sodium silicate, or mixtures of animal glue, alum,and sodium thiosulfate. An oleophilic surface may be obtained bytreatment with a dilute solution of zinc strearate and ethylcellulose-in a mixture of acetone and toluene; or with any of a numberof adhesive cement solutions containing mixtures of rubbery polymers andresinous tackifiers and modifiers in volatile organic solvents; or witha dilute solution of polyvinylidine chloride (Saran F420), followed,after drying, by a dilute solution of parafiin or spar varnish. Afiuorophilic surface is obtained by treatment with a dilute solution offluorocarbon polymer such as polyperfluorobutylacrylate orpolydihydroperfluorohexylmethacrylate; or with a dilute solution of achromium complex of a perfluoro fatty acid, applied either directly tothe copper surface or after preliminary treatment with aqueous sodiumsulfide. Variations of these surface treatments may be required wherecylinders having other than copper surfaces are to be treated; or thecylinder may first be given a plating of copper if desired. Each of thecompositions noted provides a surface or surface coating which iscapable of selectively retaining a single type of ink while beingrepellent to the remaining types. Other specific surfaces or surfacetreatments having analogous properties are contemplated, those herepresented being ofi'ered as operable and illustrative but non-limitativeexamples.

Similarly, a number of different ink formulations may be substituted forthose described in connection with the foregoing illustrative example.For the aqueous ink there has been employed a solution of a magentacolored dye in 5 percent glue solution, as well as various commercialwater-color inks and paints such as tempera paints, thinned to therequired low viscosity. Liquid parafiin oils containing variousoil-soluble dyes have been found useful as oleophilic ink compositions.For the fiuorophilic inks, best results have thus far been obtained withperfiuoroheptylated copper phthalocyanine pigment, applied in variousfiuorinated solvents such as perfluorotributylamine, perfluoro cyclicoctyl ether (particularly containing small amounts of perfiuoropolymersas viscosity-controlling agents), and perfiuoroethylcyclohexane ormixtures of perfluoroethylcyclohexane and 4-perfiuoroethylcyclohexene.

PREPARATION OF THE PRINTING SURFACE Procedure I In preparing a printingsurface for application of the activating solution, the followingillustrative precedure is found to be effective.

A base sheet 40, a portion of which is shown in FIG- URE 4, is providedwith a series of dark areas 41 in a regularly recurring pattern within acontinuous grid or screen area. Alternative positions are indicated withdotted lines for convenience. The sheet is then photographed on aprocess photographic film and the film developed in the usual manner.The resulting negative film has a series of transparent areascorresponding to the dark areas 41 .of FIGURE 4, each conveniently about0.02 inch or somewhat smaller on each side; the remainder of the film isopaque. Such a film may be identified as a /3 screen.

A second process film is exposed through the /3 screen in each of threeseparate positions, to produce a developed negative film which is opaqueat each of areas 41, 42 and 43 of FIGURE 4 and which has a transparentgrid 44 separating the opaque areas. This film may be identified as anegative full screen.

A panchromatic film is then exposed to a light-image of the coloredsubject of which prints are desired. The light passes first through acolor filter, then through the /3 screen, and finally to the film.Separate exposures are made through each of three suitable color filtersand with the /3 screen in each of three appropriate positions, so thatthe light through each filter acts on a previously unexposed portion ofthe film and in a pattern as indicated in FIGURE 4. The thus exposedfilm is next developed and reversed. There is produced a transparencyhaving a fully opaque grid corresponding to the grid 44 of FIG- URE 4,and three groups of partial-1y transparent areas corresponding to areas41, 42 and 43 of FIGURE 4 in which each group corresponds to a singlecomplementary color of the subject and the degree of transparency of theindividual areas corresponds to the relative intensity or value of thatsingle complementary color at the particular area involved. The filmthus produced may be identified as a gray image film.

Sensitized carbon tissue, having a light-senitive bichromated gelatinsurface coating, is first strongly exposed through the negative fullscreen and then given a controlled exposure through the gray image film.The grid pattern of the latter during exposure is made to coincide withthe position previously occupied by the grid pattern of the negativefull screen.

The gelatin film is next transferred to the clean surface of the coppercylinder and the design developed by washing. Chemical etching of thecopper through'the gelatin layer, and removal of the latter, thencompletes the process and produces a cylinder having a surface similarto that indicated in FIGURES 2 and 3. The surface is then ready foractivation.

While the hand-activation method previously described is effective, andhas been applied over small areas with a screen pattern having colorareas as small as 0.02 inch on a side, the method is tedious andtime-consuming. The improved method now to be described makes possiblethe simultaneous activation of an entire surface area, containing agreat number of individual printing areas for a single color. In thismethod, a photographic negative of the /3 screen previously described isfirst prepared. The previously transparent areas of the /3 screen, i.e.,the areas corresponding to the dark areas 41 of FIGURE 4, here becomeopaque, the remainder of the screen being transparent. A thin, flexible,dimensionally stable foil, preferably a metal foil, coated withlight-sensitive bichnomated gelatin, is exposed through this negativeand is then subjected to chemical etching through the gelatin mask tothe degree necessary to remove alll of the metal at the areascorresponding to the opaque areas of the negative. By means of suitablemicrometer controls, the cleaned perforated foil is positioned over theetched pattern of the gravure cylinder with the perforations lying abovethe etched cavities corresponding to a single color and with theunperforated areas of the foil covering and protecting the cavities ofthe other colors and the intervening grid. The desired activatingsolution is then applied through the perforations to the cavities,conveniently by lightly pressing a sect-ion of blotting paper, saturatedwith the ap propriate solution, against the exposed foil surface. Theprocess is repeated, with intermediate thorough washing and drying, forthe other two sets of cavities and with activating solutions appropriateto the other two colored inks. The completely activated cylinder is thenready to be placed in the press for simultaneous three-color printin goperations as hereinbefore described.

The procedure is illustrated in FIGURE 5. The perforated foil 50 havingperforations 51 corresponding to the darkened areas 41 of the base sheet40 of FIGURE 4 is placed over the etched plate 7 with the perforations51 aligned with cavities 2 and 5 corresponds to a single color. Thesection of blotting paper 52, saturated with the appropriate treatingsolution, is placed over the foil 50, permitting the solution to beexpelled into the cavities 2 and 5 of the plate 7 and rendering the samereceptive of the appropriate colored ink.

More viscous sensitizing solutions are more conveniently applied byapplying them directly to the perforated metal foil in position on theetched cylinder, e.g., by means of a rubbery squeegee as inscreen-printing.

The same type of mask may be employed in intensifying the value of oneor more of the colors to be printed, by permitting selective additionaletching and deepening of the corresponding cavities. The mask may beprotected by coating or plating with suitable polymeric, metallic, orother protective layers. Where flat plates rather than cylinders are tobe masked, the mask may be held tightly in position by direct pressureor under edge tension with the plate temporarily convexly curved.

Procedure II An alternative multicolor printing process combines theprinciples of this invention, as hereinbefore noted, with procedures andprinciples of intaglio half-tone printing, in which the ink-acceptingcavities are all of substantially equal depth but vary in area inverselywith the intensity of the light image. In this process, the A screen ismaintained a sufficient distance from the panchromatic photographic filmto act as a half-tone screen. The film is exposed to the light-imagewith the /3 screen in each of the three required positions, through theappropriate color filters, and with the appropriate lens stop asrequired for half-tone procedures. Alternatively, the /3 screen may beused in conjunction with a suitable conventional half-tone screen orcontact screen of identical spacing but more appropriate size openings.The film is developed and reversed. T he copper cylinder is coated witha photosensitive resist film of bichromated gelatin or the like, exposedthrough the positive film, developed, and etched, all by knownprocesses. The etched cylinder is then activated for the severalrequired types of inks, employing the activating solutions previouslydescribed and applying them successively through the perforated metalfoil mask in each of the appropriate positions. It is then ready formultiple-color printing.

In this intaglio half-tone process the effective color values in thefinished print are determined by the relative areas rather than therelative depths of the ink-receptive cavities in the printing surface.However it will be noted that in both of the processes described theeffective color value is a function of the volume of the printingcavities.

Procedure III Another system for preparing the printing surface involvesthe use of a multiple-color mosaic screen or filter plate and thussimplifies the preparation of the gray image film from which thephotosensitive resist is prepared. For three-color printing, the filterplate is provided with alternate red, green and blue filter areascorresponding to areas 41, 42 and 43, respectively, of FIGURE 4.

A three-color filter plate is easily prepared by separately exposing aKodachrome photographic color film or plate to light of each of thethree desired colors through the /3 screen in each of the threepositions. Development of the film then provides the desired recurringpattern of groups of areas in the three desired filter colors, the areasin this instance being separated by an opaque grid. Such a plate is notentirely effective as a color filter due to inherent low colorselectivity in the filter areas. A preferred type of screen or filter ismade by screen-process coating of a transparent base with appropriatelycolored lacquer or gelatin solutions through the perforated metal foilpreviously described under Procedure I in connection with activation ofthe cavitated printing-plate. The perforated screen is placed in each ofthe three positions and an appropriately colored coating compositionapplied in each position. The resulting filter again has the desiredrecurring pattern of groups of unit areas in the three filter colors,but has a transparent separating grid. Effective results may also beobtained by uniformly enlarging the color areas and eliminating thetransparent grid portions of the filter.

This three-color mosaic filter plate is placed in contact with apanchromatic film and the film is exposed through the filter to thelight-image of the original colored article. The film is then developedand reversed, providing a recurring pattern of groups of unit areasdiffering in density in accordance with the color and color value of theoriginal. Sensitized carbon tissue is exposed through this gray imagefilm and separately throughthe negative full screen, the gelatin film istransferred to the printing surface, and the latter is selectivelyetched and activated, as described in connection with Procedure I, toprovide the desired onepass multicolor intaglio printing surface.

The procedures hereinbefore described have been discussed primarily inconnection with the preparation and use of rotogravure cylinders forcontinuous one-pass multicolor printing. It will be apparent that thesame principles are equally applicable to printing from flat plates. Inplace of the square rulings illustrated in FIG- URES 3 and 4,triangular, hexagonal, circular, or various other rulings will likewisebe found to be effective. It will be understood that the single isolatedcavities of FIGURES 2 and 3 may be replaced by groups of smallercavities. Likewise, groups of the larger cavities may be activated,either by hand or mechanically, for application of a single color in theprinting of maps, comic supplements, and other large-area items.Application of several inks from a single fountain as indicated inconnec-. tion with FIGURE 1 is advantageous for a number of reasons andis preferred; but separate fountains for each ink may alternatively beused, or the inks may be applied by brush, roll, squeegee, or in variousother ways. Various other modifications and extensions of the principlesof the invention will become apparent from a study of the disclosuresherein provided and such alterations and extensions are contemplated ascoming within the scope of the present invention as defined in theappended claims.

What is claimed is as follows:

1. A method of preparing a printing surface for onepass multicolorintaglio printing with a plurality of differently colored and mutuallyincompatible liquid inks, comprising the steps of: (a) forming on aphotosensitive resist layer a recurring pattern of groups of unit areas,at least one unit area of each group corresponding to each color to beprinted, each unit area being photoexposed to a degree inverselycorresponding to the color value of its corresponding color at thatpoint, the unit areas being separated by a uniformly intenselyphotoexposed pattern of grid lines; (b) removing unexposed resistmaterial and chemically etching a smooth printing surface through theremaining resist layer to the point of incipient etching of the areasdirectly underlying said grid lines, to provide in the printing surfacea plurality of cavities corresponding to said unit areas and separatedby ridges having a common surface plane; and (c) activating the cavitiescorresponding to each col-or for wettability solely by the correspondingone of the said mutually incompatible differently colored liquid inks.

2. An article having a printing surface suitable for one-pass intaglioapplication of a plurality of mutually incompatible liquids, saidprinting surface comprising liquid-receiving cavities arranged in arecurring pattern of groups of cavities, each group including, for eachof said liquids, at least one cavity which is wetted solely by that oneof said liquids.

3. An article having a printing surface suitable for one pass multicolorintaglio printing with a plurality of mutually incompatible liquid inks,said printing surface comprising ink-receiving cavities and interveningridges, said ridges having a common surface plane, said cavities beingarranged in a recurring pattern of groups of cavities, each groupincluding, for each of said inks, at least one cavity which is wettedsolely by that one of said inks, the volume of each cavity being inaccordance with the color value of the corresponding color required atthe corresponding point in the print.

4. An article as defined in claim 3 and having a plurality of groups ofcavities, in which each group of cavities is distinct in wettabilityfrom each other group and is wettable by a single composition from theclass consisting of hydrophilic, organophilic and fiuorophiliccompositions.

5. In one-pass multiple-liquid intaglio printing from a printing surfaceas defined in claim 2, the steps comprising: providing at said surface aplurality of mutually incompatible liquids each capable of wetting asingle species of activated cavities and in amount just sufficient tofill each cavity with an appropriate liquid; and contemporaneouslytransferring the liquids from the printing surface to a receptivesurface which. is to be printed.

6. In one-pass multicolor intaglio printing from a printing surface asdefined in claim 3, the steps comprising: applying to said surface anexcess amount of a number of mutually incompatible liquid inks equal tothe number of different species of activated cavities, each ink beingcapable of wetting a single species of said activated cavities; removingfrom said printing surface all ink in excess of that required to fillsaid cavities; and contemporaneously transferring the inks remaining insaid cavities to an ink-receptive surface.

7. The method of selectively treating cavities in a onepass multicolorintaglio printing surface having a recurring pattern of groups ofcavities, adapted for printing with a plurality of difierently coloredand mutually incompatible liquid inks, comprising placing over saidsurface a close-fitting fractional stencil having stencil openingsaligned with cavities corresponding to a first color, and applyingthrough said openings a chemical treating solution for rendering thecavities selectively receptive of an appropriate colored ink; andrepeating the operation at cavities corresponding to each additionalcolor; so as to activate the cavities corresponding to each color forwettability solely by the corresponding one of said inks.

8. A method of preparing a printing surface for onepass multicolorintaglio printing with a plurality of differently colored mutuallyincompatible liquid inks, comprising the steps of: (a) providing on ametallic printing surface a recurring pattern of groups of ink-receivingcavities, each group including at least one cavity corresponding to eachof the colors to be printed, each cavity having a volume correspondingto the color value of the color to be printed at that point, saidcavities being separated from each other by ridges having a commonsurface plane; (b) placing over said surface and against said ridges afractional stencil having stencil openings aligned with those of saidcavities corresponding to one of said colors; (c) applying a chemicaltreating solution through said opening to said corresponding cavities torender said cavities selectively receptive of an ink composition of thesaid one of said colors; and (d) repeating steps (b) and (c) at cavitiescorresponding to each remaining color; so as to activate the cavitiescorresponding to each color for wettability solely by the correspondingone of said inks.

9. A method of preparing a printing surface for onepass intaglioapplication of a plurality of chemically different mutually incompatibleliquids, comprising the steps of: (a) forming on a photosensitive resistlayer a recurring pattern of groups of unit areas, at least one unitarea of each group corresponding to each of said liquids to be printed,the unit areas being separated by a uniformly instensely photoexposedpattern of grid lines; (b) removing unexposed resist material andchemically etching a smooth printing surface through the remainingresist layer to the point of incipient etching of the areas directlyunderlying said grid lines, to provide in the printing surface aplurality of cavities corresponding to said unit areas and separated byridges having a common plane; and (c) activating the cavitiescorresponding to each of 10 said emit areas for wettability solely bythe corresponding one of said liquids.

10. In one-pass multicolor intaglio printing from a printing surface asdefined in claim 3, the steps comprising: applying to said surface anexcess amount of an ink mixture consisting of a number of mutuallyincompatible liquid inks equal to the number of dilferent species ofactivated cavities, each of said inks being capable of wetting a singlespecies of said activated cavities; removing from said printing surfaceall ink in excess of that required to fill said cavities; andcontemporaneously transferring the inks remaining in said cavities to anink-receptive surface.

11. An article having a printing surface having a plurality of groups ofdifferently selectively ink-accepting cavities, at least one cavity ofeach group being fluorophilic.

12. An article having a printing surface suitable for one-passthree-color intaglio printing, said printing surface comprisingliquid-receiving cavities arranged in a recurring pattern of groups ofcavities, each group including at least one cavity having a hydrophilicsurface for retaining an aqueous liquid, at least one cavity having anoleophilic surface for retaining an oily liquid, and at least one cavityhaving a fluorophilic surface for retaining a fluorochemical liquid.

References Cited by the Examiner UNITED STATES PATENTS 1,673,060 6/28Brinkmann 101152 1,817,435 8/31 Freuder 101-170 1,886,597 11/32 Schwabe.2,090,704 8/37 Rowell l0l-149.2 X 2,210,923 8/40 Jacquerod et al 101-395X 2,316,708 4/43 Ormond 101-211 2,373,060 4/45 Sojka 101149.2 2,381,7538/45 Irion. 2,384,857 9/45 Terry 101149.2 X 2,560,881 7/51 Mayhew 106-202,567,963 9/51 Petke 106-22 2,625,734 l/53 Law. 2,823,146 2/ 58 Roberts.

FOREIGN PATENTS 225,015 11/24 Great Britain.

DAVID KLEIN, Primary Examiner.

ROBERT A. LEIGHEY, ROBERT E. PULFREY,

Examiners.

3. AN ARTICLE HAVING A PRINTING SURFACE SUITABLE FOR ONEPASS MULTICOLORINTAGLIO PRINTING WITH A PLURALITY OF MUTUALLY IMCOMPATIBLE LIQUID INKS,SAID PRINTING SURFACE COMPRISING INK-RECEIVING CAVITIES AND INTERVENINGRIDGES, SAID RIDGES HAVING A COMMON SURFACE PLANE, SAID CAVITIES BEINGARRANGED IN A RECURRING PATTERN OF GROUPS OF CAVITIES, EACH GROUPINCLUDING, FOR EACH OF SAID INKS, AT LEAST ONE CAVITY WHICH IS WETTEDSOLELY BY THAT ONE OF SAID INKS, THE VOLUME OF EACH CAVITY BEING INACCORDANCE WITH THE COLOR VALUE OF THE CORRESPONDING COLOR REQUIRED ATTHE CORRESPONDING POINT IN THE PRINT.
 10. IN ONE-PASS MULTICOLORINTAGLIO PRINTING FROM A PRINTING SURFACE AS DEFINED IN CLAIM 3, THESTEPS COMPRISING: APPLYING TO SAID SURFACE AN EXCESS AMOUNT OF AN INKMIXTURE CONSISTING OF A NUMBER OF MUTUALLY INCOMPATIBLE LIQUID INKSEQUAL TO THE NUMBER OF DIFFERENT SPECIES OF ACTIVATED CAVITIES, EACH OFSAID INKS BEING CAPABLE OF WETTING A SINGLE SPECIES OF SAID ACTIVATEDCAVITIES; REMOVING FROM SAID PRINTING SURFACE ALL INK IN EXCESS OF THATREQUIRED TO FLL SAID CAVITIES; AND CONTEMPORANEOUSLY TRANSFERRING THEINKS REMAINING IN SAID CAVITIES TO AN INK-RECEPTIVE SURFACE.